Ad Kayle is still nothing to mess around with. Her ult and passive make her formidable in any team comp, and with any focus build. AP Kayle, however, has several advantages over any AD version.
1.She can be a counter pick to Teemo
If you are tired of that little rascal, Kayle's splash is unaffected by that bothersome
blinding dart, allowing her to take on Teemo 1 for 1, often come out on top if all of her
abilities are used well.
2.Her splash allows her to team fight alot better than any AD kayle.
Her splash applies alot of damage to her target, and anyone unfortunite enough to be too
grouped up by whoever you are focusing.
3.More Convenient cooldowns
Having good cool downs on an AD champ is not impossible, but kayle is not an AD caster.
Ap adapts more easily to having alot of CDR, and still applying alot of damage over time.
In any case, Being able to throw up two judgments in one fight can save a game.

My runes are often criticized,
but my main point with these runes is the magic pen. With Kayle's passive, along with Malady and void staff in your build, you can end up doing true damage to you opponents at an impressive speed.

Although kayle can be placed in nearly any game and do well, she works best in high damage teams. If your comp has no tank, but an off tank, adding kayle can easily keep your team in the fight late game, allowing you to deal out all your damage without fear of your carries being shut down at the start of the fight.